ABCD

Example

A
B
A
_
B
B
A
_
B
B
C
19
22
24
15
 
 
A
B
C
_
_
_

Solution

A
B
A
20
B
B
A
22
B
B
C
19
22
24
15
 
 
A
B
C
6
8
3
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ABCD
ABCD

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